Rotary heat-exchanger

ABSTRACT

A rotary heat exchanger of the type having a hot gas pipe, a cold gas pipe and a rotary matrix of a refractory material situated in an interrupted part of the pipes. The matrix has longitudinal passages therethrough capable of establishing communication between said pipes. The active periphery of the matrix is compressed substantially uniformly over its whole width by an elastic peripheral collar which is made up of thin arcuate bands connected by elastic tension members.

United States Patent Jarry 1 Feb. 5, 1974 I ROTARY HEAT-EXCHANGER 75 I t I Phii- S F Primary Examiner-Albert W. Davis, Jr. 1 men or lppe Jan-y ewes rance Attorney, Agent, or Firm-Woodhams, Blanchard and [73] Assignee: Le Moteur Modeme, Billancourt, Fly

France [22] Filed: Feb. 14, 1972 21 Appl. No.: 225,753 ABSTRACT A rotary heat exchanger of the type having a hot gas [30] Foreign Application pnomy Data pipe, a cold gas pipe and a rotary matrix of a refrac- Feb. 15, France tory material situated in an interrupted part of the pipes. The matrix has longitudinal passages there- [52] US. Cl. 165/8, 165/10, 64/27 NM, through capable of establishing communication b 74/446 165/ 9 tween said pipes. The active periphery of the matrix is [51] 11''!!- Cl. F28d 19/00 compressed substantially uniformly over its whole [58] Fleld of Search 165/8, 9, 10; 74/446; width by an elastic periphei-ai collar which is made up 64/27 NM of thin arcuate bands connected by elastic tension members. [56] References Cited UNITED STATES PATENTS Horton 165/8 X 9 Claims, 9 Drawing Figures PATENTEDFEB 5w SHtEl 1 [IF 5 PATENTED 5'974 3.789.917

SHEET 2 [IF 5 PATENTEDFEB 3.189.917

' SHEET 0F 5 ROTARY HEAT-EXCHANGER The present invention concerns a rotary heatexchanger of the kind having a hot-gas pipe, a cold-gas pipe and a rotary matrix made of a refractory material provided longitudinally with canals forming cells and disposed in an interrupted part of the pipes, the said canals being capable of establishing communication between said canals.

In heat exchangers of this type, the rotating matrix which constitutes the active part of the exchanger is made of a refractory material and is fairly fragile. Furthermore, its periphery may be subjected to high centrifugal forces. Indeed, considerable differences of pressure are exerted radially on both sides of the parts of the matrix situated opposite the periphery of the sealing rings which, as is known, constitute a leak-tight joint between the upstream and downstream surfaces of the matrix and at least one of the pipe lines.

The result is that, if special precautions are not taken,

the periphery of the matrix very quickly cracks which makes it unusable. Consequently it must be dismantled and replaced fairly frequently.

So as to get over this disadvantage it has been suggested to subject the periphery of the matrix to a constant pressure intermediate in value between atmospheric pressure and the pressure inside the canals so that the centrifugal forces are reduced, whether the exchanger is working or at rest.

However, to put this arrangement into effect involves considerable complications from the fact that a leaktight cover must be provided surrounding the matrix and containing also the driving mechanism for the matrix. which necessitates the manufacture of extremely complicated, heavy, cumbersome equipment which moreover takes long to repair. Besides, the driving mechanism is then very difficult to ventilate.

One of the aims of the present invention is to overcome these drawbacks and to achieve this, a rotary heat-exchanger according to the invention is characterized in that the periphery of the matrix is compressed by a peripheral elastic collar at a substantially constant tension.

Thus a compensation of the elastic pressure forces is easily obtained by a determined amount of we stressing, which eliminates the risk of cracking the matrix.

Because the collar is elastic it continues-to exert an adequate clamping force on the periphery of the matrix, even if it is subjected to high temperatures or stresses and expands considerably.

This arrangement also does away, of course, with the need to mount the matrix in a leak-tight cover surrounding its driving mechanism, which greatly simplifies the manufacture and the repair of a rotary exchanger equipped in this way.

Also provided, according to this invention, is a heatinsulating band interposed between the matrix and the said collar.

The said band which may be constituted by a coating, material or felt, forms a heat-screen protecting the collar. Furthermore, it provides a uniform distribution of the mechanical pressure stresses between the matrix and the collar.

Preferably, the said collar is made of arcuate bands connected by elastic tension members each one of which acts between the overlapping end of two neighbouring strips.

Thereby the collar is subjected to practically equal tensions at every point of its periphery, thus perfectly balancing the forces exerted on the matrix.

Preferably again, the said elastic members include two stirrups each one of which abuts in a hook at the end of a band, both being subjected to an elastic force tending to separate them from each other.

The said elastic force may be provided by at least one set of spring washers operating against the inside faces of the stirrups and threaded on a shaft provided on .the stirrups.

According to another embodiment, the elastic members may include a flat spring each of whose ends abuts in a hook at the end of a band and an adjustment device able to position the central part of the leaf spring in relation to the said collar.

According to this embodiment, the nearer the central part of the flat spring is to the collar, the greater is the force with which its ends abut against the hooks of the band. Thus, the nearer the central part of the flat spring is to the collar, the greater is the clamping force exerted by the collar on the periphery of the matrix.

The said adjustment device may include an excentric, which provides a very easy adjustment of the clamping tension of the collar.

Preferably in this case, on at least one of the elastic members,-there is provided a thermostatic correction element inserted between the excentric and the central part of the flat spring.

This element is, of course, of the type which expands under the effect of heat, such as aneroid capsules. Thus, if the outside surface of the collar is subjected to high temperatures causing a very considerable expansion of the collar, the thermostatic correction element expands and automatically increases the tension of the collar, maintaining therefore a substantially constant clamping force which is exerted on the periphery of the matrix whatever the temperature.

According to the invention there is also provided externally a toothed ring disposed coaxially around the matrix, at least one of the said elastic members being fixed on the said ring whilst the others can move slightly circumferentially in relation to the ring.

Thereby, rotation of the toothed ring drives the matrix.

Because only one of the members is fixed on the ring and the others can move circumferentially, the generation of excessive stresses exerted on the toothed ring is avoided while still ensuring the perfect centring of the matrix inside the ring.

Again preferably, a rotary heat-exchanger according to the invention includes, one on each side of the toothed ring, two dish-shaped flanges whose lower parts are opposite each other and whose peripheral external faces provide a track for the rollers which are integral with the frame of the exchanger, at least one of these rollers being fixed to a drive shaft and having teeth engaged in the external teeth of the said ring.

By this arrangement the driving and the guiding of the toothed ring is ensured as well as the axial and radial centring of the rotating unit including the matrix, the thermal insulation, the collar, the elastic tension members and the toothed ring.

It is also understood that, in this way, the said rotating unit constitutes a sub-unit of the exchanger, which sub-unit can be preassembled before mounting and dismantled as a whole, in the case where a repair proves necessary, which makes the maintenance of the exchanger considerably easier and reduces its cost.

Preferably, the bearings of the drive-roller are fixed, whilst the bearings of at least one of the other rollers are radially movable and are subjected, in the radial direction, to an elastic return-force.

Thereby, the small defects, possibly included in the said roller-track, are not the cause of stresses, and the dimensional variations of this track, due to expansion or wear, can be compensated for automatically.

The invention just described offers further the considerable advantage that it provides for the arrangement of the whole of the drive mechanism on the periphery of the matrix. Since this periphery does not have to support a counter-pressure, the mechanism can be at atmospheric pressure and at a low temperature, which allows in its manufacture the use of materials of only average quality. Moreover, this mechanism can be cooled by forced ventilation at ambient temperature.

An embodiment of the invention and different variations will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 shows diagrammatically in axial section a rotary heat-exchanger according to the present invention;

FIG. 2 shows the same heat-exchanger in crosssection;

FIG. 3 shows, on a greater scale, the cross-section of a part of thesame exchanger,

FIG. 4 is a detailed cross-section view showing an elastic tension member;

FIG. 5 is a detailed plan view showing the overlapping ends of two neighbouring bands of the collar;

FIG. 6 is an axial section of the member of FIG. 4;

FIG. 7 is a detailed cross-sectional view of yet another embodiment of an elastic tension member;

FIG. 8 is a detailed cross-section view of yet another embodiment of an elastic tension member; and

FIG. 9 is a detailed axial-section view showing the roller-track solid with the toothed ring, and a drive roller.

The rotary heat-exchanger shown in FIG. 1 includes a low-pressure hot-gas pipe 1 and a cold-gas pipe 2 in which the gas is at high pressure and flows counter to the hot-gas flow, as the arrows 3 show. The active part of the exchanger is constituted by a rotary pyroceram matrix 4 crossed longitudinally, i.e. following the axis 5 of the exchanger, by canals forming cells. This matrix is arranged in an interrupted part of pipes l and 2 so that the canals can establish communication between the said pipes l and 2 in a known way, thus transferring the heat between the hot and cold gases.

The matrix 4 is provided, on each of its faces, with a sealing-ring 6 in gas-tight contact with the edge of compressed bellows 7 communicating with the highpressure gas pipe 2, the sealing-ring:determining the ratio of the active surfaces 8 and 9 on which depends the thermal output of the exchanger.

According to this invention, the periphery of the matrix is compressed by an elastic peripheral collar 10 at practically constant tension. A heat-insulating band 11 is interposed between the matrix 4 and the collar 10. This latter is made up of three arcuate bands of equal length 10a, 10b and 10c, connected by three elastic tension members 12, each of which operates between the overlapping ends of two neighbouring bands (FIG.

5). These elastic members may be, as FIGS. 2, 3, 4 and 7 show, each one made up of two stirrups such as 12a and 12b each of which abuts against the hooks 13b and 13a respectively at the ends of bands 10b and 10a. The stirrups 12a and 12b are subjected to an elastic force tending to separate them from each other, this force being provided by four sets 14 of spring-washers, for example in the shape of truncated cones and opposed in twos. The four sets 14 act between the inner faces of the stirrups and are threaded on shafts 15 provided on the stirrups to ensure the centring and tensioning of the washers.

Thus it appears that by means of this invention, the periphery of the matrix is firmly clamped by the collar even if the latter expands because of the heat. In fact, the expansion of the three elements going to make up the collar are absorbed by the sets 14 of spring-washers which, over a range sufficiently great, exert a practically constant force of separation between the stirrups.

According to an embodiment shown in FIG. 8, the elastic tension members include a flat spring 16 whose ends 16b and 16a abut in hooks, 13a and 13b respectively at the ends of bands 10a and 10b.

An adjusting device provides for positioning of the central part of the flat spring in relation to the collar 10. This device is made up of an excentric including two off-centre pins 17 and 18, pin 17 having a fixed axis in relation to the collar whilst pin 18 has its axis movable in relation to the collar by rotation of pin 17.

Since pin 18 is supported by a bearing 19 solid with the flat spring 16, it is clear that rotation of the excentric allows the flat spring 16, and therefore the collar 10, to be tensioned at will.

In this embodiment there is further provided on at least one of the elastic tension members, such as the one shown in FIG. 8, a thermostatic correction element, for example an aneroid capsule 20, which is inserted between the bearing 19 and the central part of the flat spring 16, which provides the advantage of an extra compensation, as mentioned above.

The apparatus for rotating the matrix is made up as follows (see FIGS. 1, 4, 7, 8 and 9).

It comprises an external toothed ring 21 disposed coaxially around the matrix 4. The coupling between the matrix and the ring is effected radially by means of one of the three elastic tension members by locking a peg 22a in a groove 23 of the stirrup 12a and axially by pins, not illustrated (FIG. 4). The two other elastic tension members also include pegs 22b and 220 but these last are slack in the openings 24b and 240 of the toothed ring 21, so that they may move slightly in relation thereto, in the direction of the circumference which offers the advantage mentioned above (FIG. 3).

In the embodiment of FIG. 7, the elastic tension member 12 to be locked on the toothed ring 21 carries a stop 25 wedged in a notch 26 of the ring.

In the embodiment of FIG. 8, the shaft of the fixed pin 17 is housed in an opening in the ring, which allows the coupling of the matrix and the ring, as well as the relative centring of toothed-wheel and matrix by means of the excentric.

The toothed wheel 21 is solid with two dished flanges whose lower parts are opposed '27 and 28 (FIG. 9).

Thus the external faces 27a, 28a of the periphery of these flanges form a track for the rollers 29, 30 and 31, one of which 29 is fixed on the drive-shaft 32 and is provided with teeth 33 engaged with the outside teeth of the toothed ring 21, thus driving the latter and the matrix therewith.

The bearings 34 of the drive-roller 29 are fixed in relation to the frame 35 of the exchanger, whilst the bearings of roller 31 are movable radially and are subjected, in the radial direction, to an elastic return force, as shown diagrammatically by a spring 36 (FIG. 2).

Thereby, the three rollers provide excellent radial and axial centring of the ring without there resulting stresses or excessive play, these being compensated by the radial movement of the bearings of roller 31.

The rotating unit of the exchanger is housed in a cover 37, defining a low pressure enclosure in communication with the hot gas of pipe 1 (FIG. 1).

The tightness between this enclosure and the drive mechanism, which is at atmospheric pressure, is provided by peripheral joints 38 held in position by leaf springs 39 and, in cooperation with the heat screens 40, channel gas leaks towards the outside to avoid subjecting the mechanism to high temperatures.

Furthermore, the mechanism receives forced ventilation by a supply of air at atmospheric pressure and low temperature, as shown by arrows 41 in FIG. 2.

It can be seen that the materials forming the drive mechanism for the matrix are perfectly protected from excessive temperatures. Thus they need be only of average quality, which reduces the cost price of the exchanger.

What I claim is:

l. A rotary heat-exchanger of the type having a hotgas pipe, a cold-gas pipe and a rotary matrix of a refractory material situated in an interrupted part of the pipes, said matrix having longitudinal passages therethrough capable of establishing communication between said pipes, comprising the improvement wherein the active periphery of the matrix is compressed at practically constant tension directly and uniformly over its whole width by an elastic peripheral collar, said collar being made up of thin arcuate bands connected by elastic tension members, each of which operates between the overlapping ends of two neighboring bands.

2. A rotary heat-exchanger according to claim 1, wherein a flexible heat-insulating band is interposed between the said thin arcuate bands and the active periphery of the matrix.

3. A rotary heat-exchanger according to claim 1, wherein said elastic tension members include two stirrups each one abutting in a hook at the end of a band and subjected to an elastic force tending to separate them from each other.

4. A rotary heat-exchanger according to claim 3, wherein said elastic force is provided by at least one set of spring-washers acting between the inner faces of the stirrups and threaded on shafts provided on the stirrups.

5. A rotary heat-exchanger according to claim 4, wherein the elastic tension members include a flat spring, each of whose ends abuts in a hook at the end of a band and an adjusting device capable of positioning the central part of the flat spring in relation to said collar.

6. A rotary heat-exchanger according to claim 5, wherein the adjusting device includes an eccentric.

7. A rotary heat-exchanger according to claim 6, wherein on at least one of the elastic tension members a thermostatic correction element is inserted between the eccentric and the central part of the flat spring.

8. A rotary heat-exchanger according to claim 1, wherein a toothed ring is externally disposed coaxially around the matrix, at least one of said elastic tension members being fixed on said toothed ring, whilst the others may move slightly in a circumferential direction in relation to thetoothed ring.

9. A rotary heat-exchanger according to claim 8, wherein two dish-shaped flanges are disposedone on each side of the toothed ring, their lower parts being opposed and the external faces of their periphery forming a track for the rollers which are solid with the frame of the exchanger, at least one of which rollers is fixed on a drive-shaft and provided with teeth in engagement with the external teeth of the toothed wheel. 

1. A rotary heat-exchanger of the type having a hot-gas pipe, a cold-gas pipe and a rotary matrix of a refractory material situated in an interrupted part of the pipes, said matrix having longitudinal passages therethrough capable of establishing communication between said pipes, comprising the improvement wherein the active periphery of the matrix is compressed at practically constant tension directly and uniformly over its whole width by an elastic peripheral collar, said collar being made up of thin arcuate bands connected by elastic tension members, each of which operates between the overlapping ends of two neighboring bands.
 2. A rotary heat-exchanger according to claim 1, wherein a flexible heat-insulating band is interposed between the said thin arcuate bands and the active periphery of the matrix.
 3. A rotary heat-exchanger according to claim 1, wherein said elastic tension members include two stirrups each one abutting in a hook at the end of a band and subjected to an elastic force tending to separate them from each other.
 4. A rotary heat-exchanger according to claim 3, wherein said elastic force is provided by at least one set of spring-washers acting between the inner faces of the stirrups and threaded on shafts provided on the stirrups.
 5. A rotary heat-exchanger according to claim 4, wherein the elastic tension members include a flat spring, each of whose ends abuts in a hook at the end of a band and an adjusting device capable of positioning the central part of the flat spring in relation to said collar.
 6. A rotary heat-exchanger according to claim 5, wherein the adjusting device includes an eccentric.
 7. A rotary heat-exchanger according to claim 6, wherein on at least one of the elastic tension members a thermostatic correction element is inserted between the eccentric and the central part of the flat spring.
 8. A rotary heat-exchanger according to claim 1, wherein a toothed ring is externally disposed coaxially around the matrix, at least one of said elastic tension members being fixed on said toothed ring, whilst the others may move slightly in a circumferential direction in relation to the toothed ring.
 9. A rotary heat-exchanger according to claim 8, wherein two dish-shaped flanges are disposed one on each side of the toothed ring, their lower parts being opposed and the external faces of their periphery forming a track for the rollers which are solid with the frame of the exchanger, at least one of which rollers is fixed on a drive-shaft and provided with teeth in engagement with the external teeth of the toothed wheel. 